In the production of hydrocarbon fluids from a subterranean reservoir through a well riser the flow, or volume of product will be effected by gas pressure at the reservoir. This pressure can vary depending on the particular location of, and on the age of the reservoir. Normally, the actuating pressure on the fluids contained in the reservoir will decrease over a period of time. Eventually it will decline to a level which is insufficient to move the fluid to the surface where it can be produced through a flow control system.
When the well produces under normal, controlled conditions, the reservoir pressure will be adequate to urge the fluid upwardly through the conductor or riser so long as the flow is regulated. The produced fluid will generally be comprised of a mixture of crude oil, pressurizing gas, and a varying quantity of water. There will also be present an amount of particulated elements such as sand, and other solids which determine the composition of the reservoir.
In view of this mixture's abrasive quality, and the high pressure and velocity at which the fluid is produced, the sand particles will have a detrimental scouring effect. The surfaces along which the mixture passes will become scored, abraded and will eventually require replacement.
It is desirable and even mandatory that the flow of fluid from an underground reservoir be regulated and closely controlled by a choke or the like. This will permit the flow rate to be accurately measured. Secondly, without such protection, a dangerous or uncontrollable condition might develop due to excessive pressure or free flow of the fluid from the well.
Maintaining the efficiency and the accuracy of any controlled well of this type is usually achieved by choking the flow. It has been experienced, that periodically either the bean which maintains the flow below a maximum level, or an adjustable valve which is regulated to provide a desired rate of flow, will have to be replaced.
In most well control systems, either a bean or a valve can be used to achieve this function. In the present arrangement, choking the flow rate to a desired level is achieved by positioning the bean, as well as a flow regulating valve, in close sequential proximity. Thus, as the bean receives a controlled flow of the produced fluid from a well, the flow will be properly regulated. Further, either of the flow controlling elements i.e., the bean and/or the valve parts, can be replaced without closing down fluid production for an extended period of time.
This is achieved in the disclosed apparatus by providing a variable flow control choke in the form of an elongated body having an inlet port at one end to receive a stream of the produced fluid. A discharge port at the body other end passes the fluid into a receiving conductor or the like.
The valve body is formed with a longitudinal cavity. A sleeve removably positioned in the cavity is maintained in place to form both a sealed arrangement with the cavity and to define a central passage in which both a bean and a valve member can be received.
The bean is positioned at the downstream end of the sleeve, and held in place by a seating collar. A valve stem, comprised primarily of a tapered seat, engages the seating collar. Thus, rotation of the valve stem will cause the latter to be adjusted longitudinally through the seating collar to regulate fluid flow which enters the bean main flow passage.